So I recently got my TAFG back together after a full teardown. I've resolved most of the minor issues, but my bookcase optos are being flagged during the startup test. I replaced both the opto boards when I had it apart. I confirmed the transmitter leds are all functioning (video camera). I removed the opto board and while replacing the 339's with sockets I found a physically broken resistor (R2 which I replaced, but no change). all diodes are good(via DMM test) on the board and the other three optos on the board are working properly and my led is lit as it should be. So what should I be looking for on the receiving transistors from the bookcase voltage wise. I've read where these can sometimes be installed incorrectly on the board, but I didn't specifically check that when checked to see if I had it wired correctly.